sleep button

I've had my Droid for a few days now and love it. Got the 2.1 update just two days after having the phone, yeah!

I know you can put the phone into sleep mode by pressing the power button, but I would like to know if there is an app or widget that I can press on the screen to put the phone into sleep mode. I think this would be more convenient than pressing the power button and you can do it with one hand.